Statically compile groovy

[samrocketman]

Makes it a little faster and reduces dependencies. Enables use within graalvm.

oracle/graal#1016 (comment)

import groovy.transform.CompileStatic
withConfig(configuration) {
    ast(CompileStatic)
}

https://stackoverflow.com/questions/29609130/when-why-would-i-want-to-use-groovys-compilestatic